Fragmentation explosive device

ABSTRACT

A fragmentation explosive device consisting of a plurality of projectiles cast within matrix material which vaporizes at the explosion temperature, wherein the projectiles are formed of a length of strip material having frangible zones at spaced intervals along the length thereof.

tates atet Inventors James E. Kenney;

Richard J. Ashenfelter, both of Toledo, Ohio Appl. No. 760,761

Filed Sept. 19, 1968 Patented May 25, 1971 Assignee Gerity-Schultz Corporation Toledo, Ohio FRAGMENTATION EXPLOSIVE DEVICE 4 Claims, 6 Drawing Figs.

US. Cl 102/67 Int. Cl F42b 13/48 Field of Search 102/67, 68,

[56] References Cited UNITED STATES PATENTS 1,256,762 2/1918 Apostoloff 102/67 2,564,751 8/1951 Cook 102/64 3,223,037 12/1965 Nooker et al 102/67 3,298,308 1/1967 Throner, Jr 102/67 FOREIGN PATENTS 4,928 9/1915 Great Britain 102/67 491,085 1/ 1919 France 102/64 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-C. T. Jordan Attorney-Wilson & Fraser ABSTRACT: A fragmentation explosive device consisting of a plurality of projectiles cast within matrix material which vaporizes at the explosion temperature, wherein the projectiles are formed of a length of strip material having frangible zones at spaced intervals along the length thereof.

PATENTEU m 5 l9?! SHEET 2 OF 2 WWI U1 6 FIG. 5

FRAGMENTATION EXPLOSIVE DEVICE BACKGROUND OF THE INVENTION The use of aircraft-delivered antipersonnel munitions in the A form of relatively small bomblets is known. In such munitions the small bomblets are initially contained in an outer container. Typically, 700 to 800 bomblets are carried in the outer container which, when released from an aircraft, will drop until the container is opened to commence an effective dispersal of the bomblets. The. bomblets are typically spherical in shape and provided with outwardly extending fins to impart rotation thereto as they fall downwardly. Also, the fins act to create a greater dispersal of the individual bomblets to create a larger pattern of destructive effectiveness. The outer shells or casings of the bomblets consist typically of a matrix of cast aluminum containing a plurality of small steel spheres cast therein. The interior of the bomblets contain an explosive charge and a fused detonator. The detonator is usually of the type which is actuated upon impact, causing an explosion of the explosive charge, which breaks up the outer shell of the bomblet and projects the steel spheres in all directions radially from the explosive charge. Since the temperature of the explosion reaches 3,000 to 4,000 C., the matrix material vaporizes allowing the steel spheres to be projected radially outwardly from the explosion.

The bomblets are made by initially placing a plurality of small steel spheres in a hemispherical mold cavity, and then forcing molten aluminum therein to fill the voids between the spheres and to conform to the configuration of the mold cavity. Two of the resultant cast hollow hemispherical articles are then bonded together after being loaded with a detonator fuse and explosive,

One of the disadvantages in the use of the spherical projectiles is that the efficiency of a rounded surface, in comparison to flat surface, when exposed to an explosive force is relatively inefficient, and therefore, the spherical projectiles have a lower velocity than the same size projectile provided with a flat surface against which the explosive forces can ,be applied.

It has been proposed to replace the spherical projectiles by a plurality of projectiles having a flat surface against which the explosive forces and pressures can act efficiently. However, it has been found difficult to insert square-type steel projectiles or slugs in the mold cavities with sufficient facility to make the process economically feasible.

It is an object of the present invention to employ a preformed array of projectiles having at least one flat surface, which can be readily placed in a mold cavity to be filled with a castable matrix material, such as zinc or aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become readily manifest to those skilled in the art from reading the following detailed description of the invention, when considered in the light of the accompanying drawings, in'which:

FIG. 1 is a fragmentary top plan view of a strip of metal notched at spaced intervals along the length thereof which is to be formed into the general shape of a mold cavity;

FIG. 2 is a sectional view of the strip of metal illustrated in FIG. 1, taken along line 2-2 thereof;

FIG. 3 is a perspective view of the material illustrated in FIGS. 1 and 2, being preformed into a hemispherical shape prior to being disposed in a mold cavity;

FIG. 4 is an exploded view of two cast hemispherical articles containing the preformed material illustrated in FIG. 3 prior to being filled with an explosive material;

FIG. 5 is a fragmentary elevational view of a modified version of the strip of notched material illustrated in FIGS. 1 and 2; and

FIG. 6 is a sectional view of the strip material illustrated in FIG. 5, taken along line 6-6 thereof.

feeding the rod automatically into DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, there is illustrated a strip 10 of metal, such as steel for example, which is notched as at 12 at spaced intervals along the length thereof, forming a plurality of spaced rectangularly shaped sections 14. Each of the individual sections 14 is connected to adjacent sections by a portion 16 of metal of smaller dimensions than the sections 14. Since the metal stock used in forming the strip 10 is typically square in cross section, the individual sections 14 are square in cross section, taken in a plane which is normal to the longitudinal axis of the strip. The particular configuration, insofar as the cross-sectional shape of the connecting portions 16, is of minor significance so long as the amount of overall metal is reduced to a sufficient quantity to allow the strip 10 to be readily bent and shaped into the form illustrated in FIG. 3, and also provides a frangible connection between the adjacent sections 14. The importance of the latter aspect will become apparent hereinafter in the description of the function and operation of the completed device. It has been found a typical example of the strip material is the employment of a 3/1 6-inch square rod stock being notched every three-sixteenth inch by a machine equipped with a special tool for effectively forming the notches 12. The notches 12 are typically of the order of one-sixteenth inch deep on all four sides of the rod, leaving a l/l6-inch square connecting portion 16 between each section 14 which is threesixteenth inch square.

The notched strip 10 is formed manually or automatically into a substantially hollow hemispherical shape as illustrated in FIG. 3. The form strip 10 may then be exposed to heat treatment, if necessary, to obtain the maximum degree of toughness and strength. At this point in the fabrication, the formed strip 10 of notched material is disposed in an appropriate cavity of the cover die of a die casting machine. It will be appreciated that this step may be accomplished either manually or automatically in high-speed production. Then, the ejector die of the die casting machine is closed and molten metal, such as zinc, is injected under pressure into the die cavity containing the formed strip 10. The injected metal will fill the voids in the die cavity around the strip 10 and the resultant product will be in the form of a hollow hemispherical article as illustrated in FIG. 4. The matrix material can be zinc, as mentioned above; or may be aluminum, plastic, or the like.

The resultant article 18 is formed with a plurality of outwardly extending fins 20 formed on the outer peripheral wall thereof. Also, the article 18 may have an annular rib and groove arrangement 22 formed in the outer lip portion thereof to cooperate as locater with a similar article 18 to enable the twohalves to fit together to provide a hollow spherical object.

When the two articles 18 are assembled together, the fins 20 are aligned and the cavities 24 at the free ends of the fins 20 cooperate to form channels to receive a connecting band 26. Typically, the edges of the connecting band 26 are crimped to suitably maintain the articles 18 together. However, before the articles 18 are so assembled, the interior is filled with an appropriate explosive charge and a detonating fuse, neither of which are illustrated in the drawings.

In use, a plurality of assembled devices commonly referred to as bomblets, each of which includes two mating articles 18, an explosive charge and suitable detonating fuse, and the connecting band 26, are loaded into a main container to be dropped from an aircraft. The main container used for this purpose usually contains in the order of 700 to 800 bomblets. The main container is dropped from an aircraft and opens at a predetermined time interval allowing the bomblets to be dropped independently of the main container. As the bomblets drop, the fins 20 impart rotation to the bomblets, which rotation arms the fuses and effectively causes the bomblets to be dispersed into a rather large area.

When the bomblets contact the ground, building, or some other object, the fuse detonates the explosive charge causing an explosion, the temperature of which is great enough to vaporize the matrix material, and the explosive forc'e breaks the frangible connection 16 between the metal sections 14 and propels the sections 14 radially outwardly from the explosion.

It will be noted that the explosive force acts against the flat inner surfaces of the sections 14 to impart great velocity to the individual sections 14. Since the sections 14 present a flat surface to the explosive forces, there is more efficient utilization of the explosive forces than would be had in the event of the use of spherical members as employed in the prior art. Also, the effectiveness of the bomblets is improved over the conventional structure in view of the greater impact of the sections 14 on contact, and the greater damage cause by a square or rectangular projectile, as compared to the smooth, round surface of the presently used spherical members.

It is believed that zinc metal would be a more acceptable matrix material than some of the other castable metals, such as aluminum, for example, since the total weight of the matrix material is small .in comparison to the overall weight of the finished bomblet. While zinc is of slightly higher weight per unit volume than aluminum, it has a lower vaporizing temperature. I

Referring to FIGS. and 6, there is illustrated a rod stock having a different cross-sectional configuration than the rod stock 10 illustrated in FIGS. 1 to 4. More specifically, the rod stock 10 is provided with a flat bottom and side surfaces, and a curved upper surface. In forming the notches 12 in the strip stock 10 only a single tool is necessary to remove the metal content at spaced intervals to form a plurality of spaced sections 14 being interconnected by connecting sections 16'. The resultant notched stock is formed into the hemispherical shape similar to that illustrated in FIG. 3 so that the curved surface of the sections 14 faces outwardly. In use, the explosive force will still react against a flat surface, while the opposite surface is curved to provide a projectile-shaped nose to the individual sections 14'. I

While mention has been made in the description to the use of zinc, aluminum, and other relatively light weight, low boiling point, castable metals, it will be understood that the invention also contemplates the use of plastic materials.

The invention-provides an economical fragmentation bomb device which may be employed for antipersonnel or antimaterial use by only varying the size of the rod stock used and/or varying the spacing of the notches to thereby vary the size of the individual sections to be projected by the force of the explosion.

In accordance with the provisions of the patent statutes, we have explained the principle and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that the invention may be practiced otherwise than as specifically illustrated and described without departing from the spirit or scope.

We claim:

1. In a fragmentation explosive device adapted to contain an explosive charge within an outer casing formed of a plurality of projectiles, the improvement comprising:

said projectiles consisting of at least one length of strip material having notches of reduced cross-sectional area relative to the cross-sectional area of said strip material formed at spaced intervals along the length thereof, said strip material wound into a substantially helical conformation with adjacent turns in spaced relation to each other to be encased in a matrix material.

2. The invention defined in claim 1 wherein strip material is rod stock having a rectangular cross section.

3. The invention defined in claim 2 wherein said strip material is steel.

4. The invention defined in claim 1 wherein said projectiles have at least one substantially flat surface disposed generally normal to the force vectors of an internally created explosive Charge. 

1. In a fragmentation explosive device adapted to contain an explosive charge within an outer casing formed of a plurality of projectiles, the improvement comprising: said projectiles consisting of at least one length of strip material having notches of reduced cross-sectional area relative to the cross-sectional area of said strip material formed at spaced intervals along the length thereof, said strip material wound into a substantially helical conformation with adjacent turns in spaced relation to each other to be encased in a matrix material.
 2. The invention defined in claim 1 wherein strip material is rod stock having a rectangular cross section.
 3. The invention defined in claim 2 wherein said strip material is steel.
 4. The invention defined in claim 1 wherein said projectiles have at least one substantially flat surface disposed generally normal to the force vectors of an internally created explosive charge. 